Scientists call for ranking system for proposals to save the world

London, Oct 27 : Scientists has called for a ranking system for proposals to repair the damage done to Earth's climate.

When it comes to repairing damage done to the Earth's climate, there's no shortage of ideas, ranging from schemes to put "sunshades" in orbit to burying the offending carbon dioxide underground.

According to a report in New Scientist, Philip Boyd of the National Institute of Water and Atmospheric Research in Dunedin, New Zealand, has said that ideas won't be enough. So, there is an urgent need to rank those proposals to work out which should undergo rigorous testing.

"The ideas for how to change our climate keep getting pumped out. They get lots of column inches," he said. "My concern is that we will reach a tipping point, people will ask what are we doing about it, and none of the schemes will have been tested," he added.

Boyd proposes that an international body such as the Intergovernmental Panel on Climate Change prioritize the schemes according to possible risks involved, how quickly they could be got of the ground, their cost, and how efficiently they would change the climate.

Climate scientist Martin Manning of the University of Victoria in Wellington agrees that a systematic ranking is needed, in part because there is little communication between research communities working on different approaches.

"If warming is to be kept at 2 degrees or so, which is what most governments are endorsing, we have to take every technology on hand, we can't be too fussy and we will make mistakes," he said.

Any assessment should be broadened to include other techniques besides geo-engineering, such as using plants for sequestration, according to Manning, who worked for the IPCC during the last assessment.

Some schemes could quickly be dismissed, but testing even one of the feasible schemes will still be a herculean task.

"We have only started to realise how complicated and interconnected Earth systems are, and scale up will be difficult," Boyd said.

The schemes that will be least prone to unexpected side effects - but potentially among the most costly - would be those based on well understood principles of physics and chemistry, such as "wind scrubbing", in which chemicals are used to absorb carbon dioxide from the atmosphere.

Boyd ranks geochemical schemes, such as transforming the carbon in carbon dioxide into bicarbonate ions that would be dissolved in the ocean as in between the two when it comes to risks of unexpected side effects.